We present a revision-based logical framework for modelling hierarchical assemblies of evolvable component systems. An evolvable component is a tight coupling of a pair of components, consisting of a supervisor and a supervisee, with the supervisor able to both monitor and evolve its supervisee. An evolvable component pair is itself a component so may have its own supervisor, or may be encapsulated as part of a larger component.

Components are modelled as logical theories containing actions which describe state revisions. Supervisor components are modelled as theories which are logically at a meta-level to their supervisee. Revision actions at the meta-level describe theory changes in the supervisee at the object-level. These correspond to various evolutionary changes in the component. We present this framework and show how it enables us to describe the architecture and logical structure of evolvable systems.